6 replacement heads for $35.99 delivered which equates to $6 a pop. Cheapest ever according to CamelX3 and certainly the cheapest I’ve ever seen them. Both black and white available to match your handle. Pack of 6 will last a year if you stick to their 60 day brush change recommendation.
These are the W (whitening) heads and technically the older model as they now have W2 and W3 heads (though Phillips directly still sells W heads in any case).
Doubt the newer models clean your teeth any better it’s more a personal preference on feel. I’ve used W heads for a while and find them comfortable.
Happy Dealing!
Cheaper on Fleabay https://www.ebay.com.au/itm/283616747311